Overhead power lines used in electric power transmission and distribution are high-voltage conductors suspended by towers. Cables of optical ground wire (OPGW), also known as “optical fiber composite overhead ground wire”, are run between the tops of the towers, serving to ground the towers and to shield the high-voltage conductors from lightning strikes.
The optical fibers within an OPGW cable can be used for data communications. Information can be encoded using the amplitude, the phase, and the polarization of the light that is propagated through the optical fibers.
There is a well-known interaction between light and a magnetic field. The Faraday effect causes a rotation of the plane of polarization which is linearly proportional to the component of the magnetic field in the direction of light propagation.